View source for No data on serial ports

The problem is related to the hardware design and the "auto shut-down" feature of the RS232 driver.
 
The RS232 transceiver used on the AMC-IP board (MAX3221) will shut down if no valid transitions are detected on receiving and transmitting side. If the connected equipment only is connected, and not sending, the transceiver will shut down when more than 30 seconds pass without data traffic from AMC-IP. The transceiver will turn back on when valid transitions are detected, but this will take some time, and data will be lost. It is stronlgy strongly recommend to do the hardware modification in order to ensure proper operation. In the new AMC-IP hardware version, PCB 8000/4, this modification is implemented.
[[Image:AMC-IP R694 R695.png|thumb|Location of R695 and R698]]
The problem applies to both serial ports.
 
Modification (PCB 8000/3 and earlier): Take away R698 and R695 and connect these to Vcc (3,3V). A picture of the modification is attached.